My Science School

  Precipitation in clouds may be initiated by two different processes. One of those is the coalescence process which is favoured in clouds that are relatively warm with high water content. In this process once the precipitation particles are formed they grow primarily by sweeping out cloud droplets on its trajectory or by combining with one another. This process depends upon various factors such as water content and droplet size.

            The second process is known as ice crystal process. Ice crystals appear to form in clouds when temperature drops down to -15 degrees Centigrade. In general, water in contact with most materials freeze at temperatures warmer than -40 degrees Centigrade, and sublimation will occur on most materials at super cooling’s. So the ice crystals present in clouds serve as ice nuclei (around which a droplet may form). So precipitation may be encouraged by exploiting one of these two mechanisms.

            Meteorological conditions essential for artificial production of rain are similar to those leading to natural rainfall. In natural rain process in convective clouds (warm clouds) one droplet in 10 6 grows to become a raindrop. This is about one droplet in five litres.

            One approach to stimulate rain in warm clouds is to increase this concentration of large droplets by spraying water from airplanes flying at cloud base. These droplets (radii of 20-30 microns) should be large enough to be in a favoured position for growth. Salt particles may also be injected in cloud base to provide centres on which cloud droplets can form. For super cooled (below freezing) clouds, the most effective seeding agent is dry ice.

            Nucleation occurs most readily on surfaces having a lattice structure geometrically similar to that of ice. The material that most closely approximates ice in lattice structure, known so far, is silver iodide (AgI).

            In case of stratiform clouds (clouds with no vertical extent but cover a large area) whose top is super-cooled, the natural precipitation process may proceed slowly due to scarcity of ice nuclei.

            In such cases the introduction of ice crystals near the cloud top by seeding AgI or dry ice may cause precipitation that would not occur otherwise. The introduction of these agents artificially into the clouds in concentration of about one per litre is expected to promote precipitation.

            Some of the clouds which cause rain are the stratus and stratocumulus clouds. Cumulonimbus clouds are the main rain clouds.

            Rainbows are arc shaped due to a simple geometrical principle. When the Sun shines after a shower, we often see an arc of beautiful colours in that part of the sky opposite to the Sun. If the rain has been heavy, the bow may spread all the way across the sky and its two ends seem to rest on the Earth below. The cause of this interesting phenomenon is the reflection and refraction of the Sun’s rays as they fall on drops of rain. As a ray passes into a drop of rain, the water acts as a tiny prism. The ray is bent, or refracted as it enters the drop and is separated into different colours. As it strikes the inner surface of the drop it is further refracted and dispersed. What we see in the heavens is a beautiful natural spectrum, produced by many drops.

            There are seven colours (wavelengths) in each bow – violet, indigo, blue, green, yellow, orange and red. But these colours blend into each other so that the observer rarely sees more than four or five clearly. Each colour is formed by rays that reach the eye at a certain angle, (about 42 degrees for primary bow and 50 degrees for secondary bow) and the angle for a particular colour never changes. The higher the Sun the lower the bow and if the Sun is higher than 40 degrees, no bow can be seen. According to simple geometrical principles, the rain drops which lie at this particular angle and direction opposite to the Sun lie in the form of a full circle of a part of it (arc). Even if there are enough rain drops to form a full circle, to an observer on Earth it will look like an arc as it is limited by the horizon. When the Sun is near the horizon, an observer on a high mountain or in a balloon may see the whole circle of the rainbow.

            The size of a rainbow is fixed by the way the Sun’s rays go through the raindrops. When a light ray strikes a raindrop, part of it is reflected and lost and part is refracted into the drop. When this ray hits the back of the drop, part of it is refracted out and part is reflected back to the front surface. Part of this reflected ray is again reflected and part is refracted back out. If the original ray hits near the centre, it will be deflected by  and return along the same path. This is how casts eyes work, but you will never see sunlight reflected this way because of the shadow cast by your head.

            But what happens if the original ray hits the raindrop off-centre? As the point of contact moves away from the centre it reaches a point where many rays return virtually in the same line, and reinforce each other to make a bright return at  from the sun line – the line from the Sun to the raindrop. These returns happen at all points around the sun- line, and combine to form a bright cone of angle  with its axis on the sun-line (see raindrop B). The light ray is split into its component wavelengths by the raindrop, and different colours are refracted by   different amounts – red less, blue more. So the bright cone shows rainbows colours, with red on the outside.

            If you look at a sunlit sky, full of raindrops, your eye will be on the surface of the bright cone of raindrops  from your antisunline – the line running from your eye to the top of your shadow on the ground. So you will see the rainbow as a circle that is  from the antisun-line, with the red on the outside. The original rays which hit the drop at the wrong place to form the rainbow will produce a very faint return, always less than from the antisun-line, and so inside the rainbow. This makes the sky appear darker above the bow.

            However, a secondary bow can form outside the primary. It is caused by a double reflection of rays striking raindrops. Some of the lost reflected light mentioned in the first paragraph can be reflected twice in the raindrop and therefore still reaches an observer on the ground as it finally exits the drop at an angle from the antisun-line. The fact it is reflected twice means the red will now be on the inside of the cone, and fainter.

            The variation in apparent size of rainbows is due o several factors. If the Sun is higher in the sky then of the rainbow’s arc will be above the horizon (where it is more visible), and hence it will seem smaller-even though it is still  from the antisolar point. The antisolar point is the point where an imaginary ray connecting the Sun and the observer meets the ground, coinciding with the top of the observer’s shadow. If the Sun is above the horizon, the antisolar point is below the horizon, if the sun is below the horizon the antisolar point will be in the sky.

            Similarly, the extent and distance of the water droplets (from the observer) can give rise to partial arcs, which obviously appear smaller than a full bow. Finally a rainbow’s relative size is subject to the same optical illusion that makes the moon appear larger when it is lower down in the sky we can more readily compare its size to the objects on the horizon. So a rainbow behind some houses may appear smaller than a rainbow spanning the open countryside.

  Warm, wet air surges upwards into the sky and cools dramatically forming thunderstorms. Some of the water inside the clouds freezes and strong air currents make the ice and water droplets bump together. This knocks tiny charged particles called electrons from the ice and so there is a build-up of electrical charge. This charge is released by a stroke of lightning. The lightning heats the air around it to an incredible 30,C (54,F), five times hotter than the surface of the Sun. this heat causes the air to expand very fast; i.e., faster than the speed of sound. It is this which causes the crash of thunder.

            If the thunderstorm is overheard, we can hear thunder and see lightning simultaneously. If it is not overheard, we can see lightning first, as light travels much faster than sound.

            By counting the seconds between the lightning and thunder and dividing by three we get the distance to the storm in kilometers and dividing by five we get the distance in Miles. Dark thunderclouds are formed on hot and humid days. A thundercloud is usually about 5 kms (3 Miles) across and 8 kms (5 Miles) high.

For a clear understanding of the subject we will have to do an experiment with two metal cups, say, the ever silver tumblers we use in our house. Let the two be considerably different in their sizes. If the two cups are filled with water and left undisturbed, the water in the smaller one cools down faster. This is because things usually cool from the surface. The cup with grater surface per unit volume cools faster. If the bigger cup is ‘n’ times higher and broader than the smaller, then its surface is ‘n’ squared times greater and the volume is ‘n’ cubed times greater. So, for each unit of the surface in the bigger cup there are ‘n’ times more volume. Hence the bigger one coos slower.

            Now let us come to the question. Our body is like a container of heat. The amount of heat per unit volume (say, every cubic centimetre) of the body is approximately the same. But the fingers and nose have a greater surface area per cubic centimetre than other parts of the body and so they cool down faster. The body makes up for the heat loss through various biological activities. But as soon as the heat is delivered to the fingers it escapes through the surface. But the rest of the body does it slower and so are a little hotter than the fingers.

            Oils are liquid fats. Fats are esters of carboxylic acids which are either saturated (do not contain double bond) or unsaturated (contain one or two double bond). These esters are derived from a single alcohol called glycerol and are called glycerides. Usually fats with greater percentage of un-saturation tend to be in liquid state and fats with greater percentage of saturation tend to be in solid state at room temperature.

            Vegetable fats are all liquid fats since they belong to esters of long chain fatty acids with one or more double bonds while most of the animal fats are solid in nature since they are all esters of long chain fatty acids which do not contain double bond.

            Coconut oil unlike other vegetable oils contains nearly 91 per cent of saturated fatty acids. Even though it has greater percentage of saturation it remains as liquid fat instead of solid fat.

            Its liquid nature is due to the presence of more number of short chains (C12 and C14) saturated fatty acids (only fats with long chain saturated fatty acids remains as solid fats). Because of the greater percentage of saturation coconut oil can easily be solidified at low temperature and becomes solid during winter when the temperature falls below 20 degree centigrade.

            Oils which contain unsaturated fatty acids can also be solidified if their double bonds are broken by hydrogenation at very high temperature. Vegetable ghee and vanaspathi are made in this way. This process is called hardening. In the case of coconut oil this hardening occurs not because of hydrogenation but because of low temperature.

 Bermuda Triangle is a section of the Western Atlantic, off the southeast coast of the U.S, forming a triangle extending from Bermuda in the north to southern Florida and then east to a point through the Bahamas past Puerto Rico to about 40 degrees west longitude and then back again to Bermuda.

       In this mysterious place, a large number of planes and ships have vanished into thin air, of them since 1945. Interestingly, of the thousands of lives lost in the past not a single body or pieces of wreckage from the vanishing planes and ships have been found.

            Many varied and imaginative explanations have been offered and seriously considered to account for the continuing disappearances and assumed (because no bodies have been recovered) fatalities.

            These include sudden tidal waves caused by earthquake, fireballs which explode the planes, attacks by sea monsters, and a time-space warp leading to another dimension, electromagnetic or gravitational vortices which cause planes to crash and ships to lose themselves at sea, capture and kidnapping by flying or submarine UFOs (Unidentified Flying Objects) manned by entities from surviving cultures of antiquity, outer space, or the future looking for specimen of currently existing earth inhabitants.

            One single common thread which unites them is the fact ships and planes have completely vanished or that the ships have been found without their crews and passengers. While isolated mysteries of this nature could be explained by unusual circumstances or coincidences of weather and human error, so many of the Bermuda Triangle incidents have happened in clear weather, near to port, shore or landing base, that they seem unexplainable according to presently held concepts.

Uttar Pradesh is the fourth largest state of India. It is bounded by Nepal, Himachal Pradesh, Haryana, Rajasthan, Madhya Pradesh and Bihar. The Gangetic Plain occupies three quarters of the state. The entire alluvial plain can be divided into three sub-regions – the eastern, central and western tracts. The Gangetic plain is watered by the Jamuna, the Ganga, and its major tributaries. The Vindhya Hills and plateau in the southern part consist of hard rock strata, with a varied landscape of hills, plains, valleys and plateau. Uttar Pradesh can lay claim to be the oldest seat of India’s culture and civilization. The findings of the archeological excavations from various places of the state link Uttar Pradesh of the early Stone Age and Harappan era.The classical dance Kathak, folk arts like Braj Raslila, Ramlila and Charkula are very famous art forms of Uttar Pradesh.

The state of Uttarakhand is surrounded by Himachal Pradesh in the north-west, and Uttar Pradesh in the south. It shares its international borders with Nepal and China. The northern part of the state of Uttarakhand is shrouded by Himalayan ranges and glaciers, whereas the lower parts of the state are thickly forested.  Situated at the height of 7,816 m above sea level, Nanda Devi in the districts of Chamoli is the highest point in the state. Two of India’s biggest rivers, the Ganga and the Yamuna originate in the glaciers of Uttarakhand. The geography of Uttarakhand is such that it is usually divided into two parts, the western half known as Garhwal, and the eastern region as Kumaon. Did you know    that the word Uttarakhand is the Sanskrit term for ‘north country’?

 

Kanchenjunga in the eastern Himalayas is situated on the border between Sikkim and eastern Nepal. It is the third highest mountain in the world, and soars to a height of 8586 metres. Its name is derived from four words of Tibetan origin that can be translated into the Sikkim language as 'five treasuries of the great snow'. 

 The Bhakra Dam is India's biggest hydro electric project. It is located near the border of Punjab with Himachal Pradesh. The dam has been constructed across the perennial river Sutlej, which flows down the Shivalik ranges that surrounds the region, and is an engineering marvel. It is one of the highest gravity dams in the world, and it has created a huge reservoir known as the Gobind Sagar reservoir. This dam is virtually the central nervous system of northern India, as it supplies electricity to the entire region.

Odisha lies on the eastern coast of India. It is bounded by West Bengal in northeast, Jharkhand in the north, Madhya Pradesh in the west, Andhra Pradesh in the south, and the Bay of Bengal in the east. Orissa can be divided into three broad regions – the coastal plains, the middle mountainous country and the plateaus. The region of the coastal plains is a combination of several deltas formed by the major rivers of Odisha, such as the Subarnarekha, the Budhabalanga, the Baitarani, the Brahmani, the Mahanadi, and the Rushikulya. The middle mountainous region covers about three-fourths of the entire state and comprises the hills and mountains of the Eastern Ghats. The plateaus are mostly eroded tablelands, forming the western slopes of the Eastern Ghats.   To sum up, the state offers diverse habitats from lush green and hilly terrain, to coastal plains and rolling river valleys, criss-crossed by rivers that include the Brahmani, the Mahanadi and the Bansadhara.

For centuries, the Naga tribes have lived in harmony with their environment. They have always been self sufficient, producing their own food, clothing, and shelter. Their culture and lifestyle show their deep respect for Nature.

Nagaland is located on the extreme north east, just below Arunachal Pradesh. The terrain is hilly, rugged, and mountainous. The highest peak is Saramati in the Twensang district, which is 3840 metres above sea level. The average height of the peaks is between 900 and 1200 metres. The hillsides are covered with green forests. In fact, 20 percent of the total area of the state is covered with wooded forest, rich in flora and fauna. The only well known lake is Lacham.The state of Nagaland is drained by four chief rivers of Doyang, Jhanji, Dhansiri and Dikhu. The rivers are the tributaries of the mighty Brahmaputra River, with their sources in the mountain ranges of the state.

Meghalaya is a tourist’s paradise and is home to some of the most pristine forests in India. With its many national parks, deep valleys, arching waterfalls, and charming villages, it is a great gateway destination indeed. Earth, Cherrapunjee, is in Meghalaya. It gets over 11,430 millimeters of rain every year, inundating virtually the entire area for months at a time and tourists flock here for the experience